A scanning electrochemical microscope probe may be fabricated as in a method proposed by Allen J. Bard et al. (Anal. Chem. 61, 1989, page 132). The detail is explained below by reference to FIG. 5.
A platinum wire 150 of several microns in diameter is put in a glass tube 151 of 1 mm in inside diameter closed at one end, and the other end of the glass tube is connected to a vacuum pump 153 to evacuate the tube. A heater wire 152 is wound around the glass tube 151, and the glass tube is melted and the platinum wire is sealed in (FIGS. 5(a), (b)). Afterwards, the front end of the glass tube 151 is polished with sandpaper and diamond paste until the platinum wire 151 is exposed to the surface (FIG. 6). Then the glass wall 151 around the platinum wire 150 is polished with emery paper (product number Grit 600 manufactured by Buehler Ltd.) and diamond paste to sharpen the end of the glass tube (FIG. 7). In this manner, the scanning electrochemical microscope probe is fabricated.
The scanning electrochemical microscope probe fabricated in the conventional process consists of a platinum wire which is a metal wire for detecting the current, and a glass tube for insulating it electrically. The outside diameter and wall thickness of the glass tube should be preferably as small as possible, but it is difficult to manufacture to a size of scores of microns or less. Therefore, the shape of the probe is determined by the shape of the glass in which the platinum wire is sealed. To sharpen the end of the probe, the glass is polished mechanically, but it is difficult to control the radius of curvature of the end of the probe within several microns by this method.
Therefore, as shown in FIG. 8, when the probe of the scanning electrochemical microscope manufactured in the conventional method is brought close to a specimen 154 of which surface is not smooth, the glass wall 151 around the platinum wire first touches the specimen 154, and the probe cannot be brought very close to the specimen, and the resolution of the specimen observation is poor.